CN110697933B - Method for controlling content of halogenated disinfection byproducts - Google Patents

Abstract

The invention discloses a method for controlling the content of halogenated disinfection byproductsSpecifically disclosed is a process of passing O₃/H₂O₂A method for controlling halogenated disinfection byproducts by combining ceramic membrane and activated carbon, belonging to the technical field of drinking water treatment in environmental engineering. In the invention, O₃Organic combination of activated carbon and ceramic membrane processes with addition of H₂O₂Thereby further enhancing the oxidation effect of the sand filtration effluent, and improving the removal efficiency of DOM in the sand filtration effluent by the combined process and controlling the generation of disinfection byproducts through the processes of fractional feeding and magnetic stirring.

Description

Method for controlling content of halogenated disinfection byproducts

Technical Field

The invention relates to a method for controlling the content of halogenated disinfection byproducts, in particular to a method for controlling the content of halogenated disinfection byproducts through O₃/H₂O₂A method for controlling halogenated disinfection byproducts by combining ceramic membrane and activated carbon, belonging to the technical field of drinking water treatment in environmental engineering.

Background

The main purpose of tap water disinfection is to control the quantity of pathogenic microorganisms in water so as to enable the effluent quality to meet the corresponding standard and meet the requirements of human production and living. However, in the disinfection process, besides playing a positive role in disinfection and sterilization, the disinfectant also reacts with natural organic matters, bromides, iodides and the like in water to generate a series of toxic and harmful substances, which are called disinfection byproducts. Disinfection byproducts pose potential health risks and are a major concern in drinking water quality management processes. Carbon-containing disinfection byproducts such as Trihalomethanes (THMs), haloacetic acids (HAAs), Chloral (CH) and the like and nitrogen-containing disinfection byproducts such as Haloacetonitrile (HANs) and Halonitromethane (HNMs) have high detectable rates in water. In the sanitary standard for drinking water (GB 5749-. Research shows that the overproof risks of three disinfection byproducts, namely TCM, DCAA and CH are high, and important attention is needed.

The method of controlling the generation of disinfection byproducts is not exclusive and controlling the generation of disinfection byproducts by removing disinfection byproduct precursors is the most common method. Since the soluble organic matter (DOM) is sterilizedImportant precursors of the by-products, and therefore the formation of by-products during the subsequent disinfection process is often controlled by removing DOM from the water. The conventional water treatment process (coagulation-precipitation-sand filtration-disinfection) is a treatment process commonly used in water treatment plants in China, mainly removes particles and suspended matters in water, but has poor DOM removing effect, so O is often adopted₃The activated carbon technology and the membrane separation technology carry out advanced treatment on tap water, but both have certain disadvantages in the using process. O is₃The disadvantages of the activated carbon process are: the conventional dosage of O is due to the sand filtrate water still containing more microorganisms, fine particles and a large amount of DOM₃Cannot completely oxidize these substances, and the excessive dosage of O₃And the microorganisms on the surface of the activated carbon are adversely affected, so that the removal efficiency of the organic matters by the activated carbon is reduced. Thus O₃Undegraded substances in the oxidation effluent can block micropores on the surface of the activated carbon in the long-term operation process, so that the adsorption capacity of the activated carbon is reduced, and the service life of the activated carbon is shortened; on the other hand, the high concentration of organic matters in the micropores of the activated carbon can also cause the breeding of a large amount of bacteria, and some bacteria can be desorbed from the surface of the activated carbon to cause the reduction of the microbial safety of the effluent quality. The membrane separation technology has good effect of intercepting particles in water and can filter microorganisms such as bacteria and viruses, so that the membrane separation technology has many advantages in the water treatment process. The ceramic membrane is an inorganic membrane, and has the obvious advantages of high temperature resistance, acid and alkali corrosion resistance, oxidation resistance and the like compared with an organic membrane. However, the ceramic membrane filtration process has an inevitable problem of membrane pollution, and the treatment efficiency of the ceramic membrane process on organic matters can be improved by relieving the membrane pollution. Therefore, O may be considered₃Organic combination of activated carbon and ceramic membrane processes with addition of H₂O₂Thereby further strengthening the oxidation effect to the sand filtration effluent, and carrying out parameter optimization to the combined process, thereby improving the removal efficiency of DOM in the sand filtration effluent by the combined process, and controlling the generation of disinfection byproducts. How to simply and effectively control the generation of the disinfection by-products of the drinking water so as to meet the requirements of the drinking water sanitary standard GB 5749-2006 still needs toTo explore further.

Disclosure of Invention

In order to solve the above problems, the present invention provides an O₃/H₂O₂A method for combining a ceramic membrane and activated carbon, aiming at the condition that a large amount of DOM in the sand filtered water is generated to cause a large amount of toxic and harmful disinfection byproducts in the chlorine disinfection process, by optimizing H₂O₂The adding amount, the adding mode and the stirring mode realize the high-efficiency removal of the disinfection by-product precursor in the water by the combined process, thereby controlling the generation of the halogenated disinfection by-product, and providing more detailed and reliable basis and more convenient and effective means for reducing the potential harm of the toxic and harmful disinfection by-product in the water to human bodies.

It is a first object of the present invention to provide a method for controlling the level of halogenated disinfection byproducts, said method comprising the steps of:

(1) taking sand, filtering to obtain water, and introducing O into the water₃And adding a certain amount of H₂O₂Stirring; said O is₃The dosage is 1.0-1.5 mg/L; said H₂O₂The volume ratio of the adding amount to the water sample to be treated is 0.05-0.3%; said O is₃/H₂O₂The oxidation time is 25-30 min;

(2) to O obtained in step (1)₃/H₂O₂Filtering the oxidized effluent by a ceramic membrane to obtain ceramic membrane effluent;

(3) adding activated carbon into the ceramic membrane effluent obtained in the step (2), and sealing and oscillating to obtain adsorbed effluent;

(4) and (4) filtering the adsorbed effluent obtained in the step (3) through a 0.45-micrometer filter membrane, and sterilizing after filtering.

In one embodiment of the invention, the sand-filtered effluent is effluent from surface water treatment by coagulation, sedimentation and sand filtration. Wherein, the DOC concentration in the sand filtered water is 4.60-5.80 mg/L, the TDN concentration is 0.66-1.02 mg/L, and NH is added₄ ⁺N concentration of 0.35-0.62 mg/L, NO₃ ^-N concentration of 0.10 to 0.18mg/L, NO₂ ^-The concentration of-N is 0.01-0.04 mg/L, and the concentration of DON isDegree of 0.25 to 0.33mg/L, UV₂₅₄Between 0.030 and 0.044.

In one embodiment of the present invention, said O is₃/H₂O₂The stirring mode in the oxidation process is one of magnetic stirring, mechanical stirring and micro-aeration stirring, and preferably, the stirring mode is magnetic stirring.

In one embodiment of the present invention, the H₂O₂Is 30% of H₂O₂An aqueous solution.

In one embodiment of the present invention, the H₂O₂The adding amount is preferably 0.15-0.2%.

In one embodiment of the present invention, the H₂O₂The adding mode is one of one adding, two adding and three adding.

In one embodiment of the present invention, further, the H is₂O₂The adding mode is preferably two times or three times.

In one embodiment of the invention, H is added twice₂O₂The adding amount of the two times before and after the middle time is respectively 0.05-0.25 percent and 0.05-0.25 percent, and the adding time of the two times is respectively the beginning time of the reaction and the 10-20 min time of the reaction.

In one embodiment of the invention, H is dosed three times₂O₂The adding amount of the first time and the second time is 0.02-0.1%, 0.02-0.1% and 0.02-0.1%, preferably, the adding amount of the first time and the second time is the same, and the adding time of the third time is the beginning of the reaction, the 5-10 min of the reaction and the 15-20 min of the reaction.

In one embodiment of the invention, preferably, two additions of H are made₂O₂Firstly adding 0.1 percent of the raw materials, performing magnetic stirring reaction for 15min, then adding 0.05 percent of the raw materials, and performing magnetic stirring for 15 min.

In one embodiment of the invention, preferably, three additions of H are made₂O₂The addition is carried out once every 10min, 0.05 percent of the addition is carried out every time, and the mixture is magnetically stirred.

In one embodiment of the invention, the ceramic membrane is one of ceramic membranes having a pore size of 0.05 μm, 0.10 μm or 1 μm.

In one embodiment of the present invention, the activated carbon is powdered activated carbon.

In one embodiment of the invention, the adding amount of the activated carbon is 8-12 mg/L.

In one embodiment of the present invention, the adsorption time of the activated carbon is 30 to 60 min.

In one embodiment of the invention, the activated carbon adsorption process is performed on an oscillator, and the rotation speed of the oscillator is 100-130 r/min.

In one embodiment of the invention, the disinfectant is a sodium hypochlorite solution, and the disinfection conditions are as follows: adding 30mg/L of chlorine, reacting at 24-26 ℃ and pH 6.5-7.5 in a dark place for 24 hours.

A second object of the invention is to apply the above process in the field of environmental protection.

The invention has the beneficial effects that:

(1) with O alone₃Oxidation phase ratio, O₃/H₂O₂The combined use can generate more hydroxyl free radicals, has fast reaction and strong oxidation capability, can directly oxidize cells, destroy enzymes necessary for bacteria, fungi and algae, can fully oxidize organic matters in the sand filtration effluent and has no secondary pollution.

(2) Compared with once adding H₂O₂By adding the raw materials in different times, the O content can be obviously improved₃/H₂O₂The oxidation efficiency of the organic matters.

(3)O₃/H₂O₂The synergistic oxidation is beneficial to slowing down the pollution of the ceramic membrane, reduces the cost of membrane cleaning and prolongs the service life of the membrane.

(4) Magnetic stirring can be performed in a sealed environment, reducing O compared to mechanical stirring and aeration stirring₃And H₂O₂The decomposition or dissipation speed improves the utilization rate and reduces the cost.

(5) The ceramic membrane can intercept the large molecules and the medium molecular weight organic matters in the oxidized water, and the active carbon has good removing effect on the small molecular weight organic matters, so that the ceramic membrane and the active carbon are combined to play a complementary role, and the organic matters in the water are completely removed.

(6) The method of the invention is used for further processing the sand filtration effluent, the generation amount of disinfection byproducts can be greatly reduced, and the concentrations of the generated TCM, DCAA and CH all meet the requirements of drinking water sanitary standard GB 5749-.

(7) The method is simple to operate, does not relate to toxic and harmful reagents, and is favorable for popularization.

Detailed Description

1. Determination of DOC Using TOC Total organic carbon Analyzer (TOC-VCPH, Shimadzu corporation)

The concentration of soluble total nitrogen (DTN) was measured using a fully automatic continuous flow Analyzer (Auto Analyzer 3, SEAL, germany); spectrophotometry with Nyquist reagent for NH₄ ⁺-N is measured; by UV spectrophotometry of NO₃ ^--N is measured; spectrophotometry of N- (1-naphthyl) -ethylenediamine for NO₂ ^--N is measured; DON is represented by the formula: DON ═ TN-NH₄ ⁺-N－NO₃ ^--N－NO₂ ^--N is calculated; UV-light using UV-spectrophotometer₂₅₄Carrying out measurement; the residual chlorine is measured by adopting an N, N-diethyl-p-phenylenediamine spectrophotometry. Spectrophotometry of indigo disulfonic acid sodium (IDS) for O in water₃The concentration was measured.

2. Determination of TCM and CH disinfection byproducts

Adding 20mL of the sterilized water sample into a 50mL sample bottle; 4mL of methyl tert-butyl ether (MTBE) was added, and 6g of anhydrous Na dried at high temperature was immediately added₂SO₄(ii) a Oscillating on a vortex oscillator for 2min to fully extract; standing for 30min to separate the upper organic phase from the lower aqueous phase; the upper organic phase (1 mL) was aspirated, and the resulting solution was placed in a gas vial and measured by a gas chromatograph (GC-ECD).

3. Determination of DCAA Disinfection by-product

Adding 20mL of the sterilized water sample into a 50mL sample bottle; into a water sampleAdding 1mL of concentrated sulfuric acid; 6g of anhydrous Na dried at high temperature was added₂SO₄Oscillating for 1min on a vortex oscillator; adding 4mL of MTBE, and extracting for 2min on a vortex oscillator to fully extract; standing for 30min to separate the upper organic phase from the lower aqueous phase; sucking 2mL of organic phase into a 10mL sample bottle, adding 2mL of acidified methanol (containing 10% sulfuric acid), and uniformly mixing; placing the mixture in a water bath kettle at 50 ℃ for reaction for 2 hours; taking out, cooling, adding 5mL of Na₂SO₄Shaking the solution (150g/L), standing and layering; sucking the lower layer aqueous solution until the lower layer aqueous solution is not more than 0.5 mL; 1mL of fresh saturated NaHCO was added₃Uniformly mixing the solution, opening a bottle cap to release gas, and standing for 5 min; the upper organic phase (1 mL) was aspirated, and the resulting solution was placed in a gas vial and measured by a gas chromatograph (GC-ECD).

Example 1:

1000mL of sand-filtered water (basic properties are shown in Table 1) was taken, and 1.0mg/L of O was introduced into the water₃Respectively adding H of 0.5mL, 1.0mL, 1.5mL, 2.0mL and 3.0mL in one step₂O₂The reaction was magnetically stirred in a sealed vessel for 30 min. After 30min, the oxidized water body is filtered through a ceramic membrane with the aperture of 1 mu m. Collecting the ceramic membrane effluent into a 1000mL conical flask, adding 10.0mg/L of activated carbon into the conical flask, and placing the conical flask on an oscillator for oscillation. After adsorption for 30min, the water was taken out, filtered through a 0.45 μm filter and disinfected, the results are shown in Table 2.

TABLE 1 basic physicochemical Properties of Sand-filtered effluent

TABLE 2 amounts of 3 disinfection by-products formed in example 1

H2O2Dosage (mL)	TCM(μg/L)	DCAA(μg/L)	CH(μg/L)
				0.5	47.03	43.47	9.83
1.0	39.86	37.87	7.78
				1.5	33.90	30.40	6.18
2.0	31.19	26.14	5.38
				3.0	35.53	29.87	7.21

When H is shown in Table 2₂O₂When the amount of (b) is in the range of 0.5mL to 2.0mLThe amount of the by-product of disinfection is dependent on H₂O₂The dosage is increased and decreased continuously. H₂O₂When the amount of (2) was 0.5mL, the amount of TCM produced was 47.03. mu.g/L, the amount of DCAA produced was 43.47. mu.g/L, and the amount of CH produced was 9.83. mu.g/L. When H is present₂O₂When the amount of (2) was increased to 2.0mL, they were decreased to 31.19. mu.g/L, 26.14. mu.g/L and 5.38. mu.g/L, respectively. But when H₂O₂When the amount of the added substance (C) is continuously increased to 3.0mL, the control of the disinfection by-products is adversely affected. Thus in O₃When the adding amount is 1.0mg/L, H₂O₂The amount of the additive is preferably 1.5 to 2.0 mL.

Example 2:

1000mL of sand is taken to filter out water, and 1.0mg/L of O is introduced into the water₃And 1.5mL of H was added thereto₂O₂The adding modes are respectively as follows: 1.5mL of the solution is added at a time, and the solution is magnetically stirred and reacts for 30 min; adding 1.0mL of the mixture, performing magnetic stirring reaction for 15min, then adding 0.5mL of the mixture, and performing magnetic stirring for 15 min; adding the mixture once every 10min, adding 0.5mL of the mixture every time, and magnetically stirring. After 30min, filtering the oxidized water body by a ceramic membrane with the aperture of 1 mu m; collecting the ceramic membrane effluent into a 1000mL conical flask, adding 10.0mg/L of activated carbon into the conical flask, and placing the conical flask on an oscillator for oscillation; after adsorption for 30min, the water was taken out, filtered through a 0.45 μm filter and disinfected, the results are shown in Table 3.

TABLE 3 amounts of 3 disinfection by-products formed in example 2

Feeding mode	TCM(μg/L)	DCAA(μg/L)	CH(μg/L)
				Is added once	33.90	30.40	6.18
Adding twice	29.88	24.13	5.82
				Adding for three times	28.11	22.06	5.37

As can be seen from Table 3, by adding H in two or three portions₂O₂Compared with a one-time adding mode, the mode has better control effect on the disinfection by-products. The effect difference between the two-time feeding and the three-time feeding is small, and the two-time feeding mode is preferred.

Comparative example 1:

not via O₃/H₂O₂Ceramic membrane-active carbon treatment, but directly disinfecting the sand filtration effluent after filtering with a 0.45 mu m filter membrane. The amounts of generated TCM, DCAA and CH are 65.27 mug/L, 59.44 mug/L and 15.93 mug/L respectively, and 3 disinfection byproducts are overproof. This indicates that conventional processes are inefficient in the removal of the precursor disinfection by-products and further treatment of the sand filtration effluent is necessary.

Comparative example 2:

referring to example 2, two additions of H were used₂O₂And magnetic stirring is changed into mechanical stirring. The results show that the amounts of TCM, DCAA and CH are respectively 40.18. mu.g/L, 32.22. mu.g/L and 8.22. mu.g/L, and 3 disinfection byproducts do not exceed the standard but are higher than the concentrations of the 3 disinfection byproducts after magnetic stirring. This is illustrated in O₃/H₂O₂In the oxidation process, magnetic stirring is adopted as much as possible. Meanwhile, mechanical stirring can also be used as an alternative mode, and the reaction speed of the substrate and the oxidant can be increased by the two stirring modes, so that the generation of disinfection byproducts can be effectively controlled.

Comparative example 3:

referring to example 2, two additions of H were used₂O₂And changing the magnetic stirring into aeration stirring. The results show that the amounts of TCM, DCAA and CH are respectively 62.38 mug/L, 53.07 mug/L and 13.87 mug/L, and 3 disinfection byproducts are all out of standard. This is illustrated in O₃/H₂O₂In the oxidation process, aeration and O are avoided as much as possible₃And H₂O₂Which decomposes too rapidly in water resulting in a decrease in oxidation efficiency.

Comparative example 4:

with reference to example 1, using O₃Ceramic membrane treatment, other conditions were the same as in example 1. The results showed that the amounts of TCM, DCAA and CH produced were 56.22. mu.g/L, 55.35. mu.g/L and 12.21. mu.g/L, respectively.

Comparative example 5:

with reference to example 1, using O₃Activated carbon treatment, otherwise conditions were the same as in example 1. The results showed that the amounts of TCM, DCAA and CH produced were 51.69. mu.g/L, 52.68. mu.g/L and 11.19. mu.g/L, respectively.

Comparative example 6:

with reference to example 1, using O₃Ceramic membrane-activated carbon treatment, other conditions were the same as in example 1. The results showed that the amounts of TCM, DCAA and CH were 47.53. mu.g/L, 49.66. mu.g/L and 10.51. mu.g/L, respectively.

Comparative example 7:

with reference to example 1, using H₂O₂Ceramic membrane-activated carbon treatment, other conditions were the same as in example 1. The results showed that the amounts of TCM, DCAA and CH produced were 54.88. mu.g/L, 55.15. mu.g/L and 11.08. mu.g/L, respectively. As can be seen by combining example 1 and comparative examples 4 to 7, O is used₃Ceramic membrane treatment, O₃Activated carbon treatment and O₃The control effect on the disinfection by-products is not as good as that of O during the ceramic membrane-activated carbon treatment₃/H₂O₂-pottery (R) -clayCeramic film-activated carbon treatment effect. This indicates that O₃/H₂O₂The ceramic membrane-activated carbon treatment can well remove organic matters in the sand filtered water, and achieves a good effect on the control of disinfection byproducts.

TABLE 4 amount of disinfection by-products of different treatment methods

	TCM(μg/L)	DCAA(μg/L)	CH(μg/L)
				Example 2	29.88	24.13	5.82
Comparative example 1	65.27	59.44	15.93
				Comparative example 2	40.18	32.22	8.22
Comparative example 3	62.38	53.07	13.87
				Comparative example 4	56.22	55.35	12.21
Comparative example 5	51.69	52.68	11.19
				Comparative example 6	47.53	49.66	10.51
Comparative example 7	54.88	55.15	11.08

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (9)

1. A method of controlling the level of halogenated disinfection byproducts, comprising the steps of:

(1) taking sand, filtering to obtain water, and introducing O into the water₃And adding a certain amount of H₂O₂Stirring; said O is₃The dosage is 1.0-1.5 mg/L; said H₂O₂The adding amount is 0.05% -0.3%; said O is₃/H₂O₂Oxidation by oxygenThe time is 25-30 min;

(2) to O obtained in step (1)₃/H₂O₂Filtering the oxidized effluent by a ceramic membrane to obtain ceramic membrane effluent;

(3) adding activated carbon into the ceramic membrane effluent obtained in the step (2), and sealing and oscillating to obtain adsorbed effluent;

(4) filtering the adsorbed effluent obtained in the step (3) through a filter membrane, and then disinfecting the filtered effluent;

wherein, the H₂O₂The adding mode is one of two times of adding and three times of adding, and H is added twice₂O₂The adding amount of the two times is 0.05-0.25% and 0.05-0.25% respectively, and the adding time of the two times is the beginning of the reaction and the 10-20 min of the reaction respectively; adding H for three times₂O₂The adding amount of the mixture is 0.02-0.1%, 0.02-0.1% and 0.02-0.1% respectively before and after the adding, and the adding time of the mixture is the beginning of the reaction, the 5-10 min of the reaction and the 15-20 min of the reaction respectively;

said O is₃/H₂O₂The stirring mode in the oxidation process is magnetic stirring;

the DOC concentration in the sand filtered water is 4.60-5.80 mg/L, the TDN concentration is 0.66-1.02 mg/L, and NH is added₄ ⁺N concentration of 0.35-0.62 mg/L, NO₃ ^-N concentration of 0.10 to 0.18mg/L, NO₂ ^-A concentration of-N is 0.01 to 0.04mg/L, a concentration of DON is 0.25 to 0.33mg/L, UV₂₅₄In the range of 0.030-0.044 cm^-1To (c) to (d); said H₂O₂Is 30% of H₂O₂An aqueous solution.

2. The method of claim 1 wherein said H is selected from the group consisting of₂O₂The adding amount is 0.15% -0.2%.

3. A method of controlling the level of halogenated disinfection byproducts as claimed in claim 1 or claim 2 wherein said ceramic membrane is one of ceramic with a pore size of 0.05 μ ι η, 0.10 μ ι η, or 1 μ ι η.

4. The method for controlling the content of halogenated disinfection byproducts as claimed in claim 1 or 2, wherein the adding amount of the activated carbon is 8-12 mg/L; the adsorption time of the activated carbon is 30-60 min.

5. The method for controlling the content of halogenated disinfection byproducts as claimed in claim 3, wherein the adding amount of the activated carbon is 8-12 mg/L; the adsorption time of the activated carbon is 30-60 min.

6. A method for controlling the level of halogenated disinfection byproducts as claimed in any one of claims 1, 2 or 5 wherein said disinfectant is sodium hypochlorite solution and the disinfection conditions are: adding 30mg/L of chlorine, reacting at 24-26 ℃ and pH 6.5-7.5 in a dark place for 24 hours.

7. A method for controlling the level of halogenated disinfection byproducts as claimed in claim 3 wherein said disinfectant is sodium hypochlorite solution and the disinfection conditions are: adding 30mg/L of chlorine, reacting at 24-26 ℃ and pH 6.5-7.5 in a dark place for 24 hours.

8. The method of claim 4, wherein the disinfectant is a sodium hypochlorite solution and the disinfection conditions are as follows: adding 30mg/L of chlorine, reacting at 24-26 ℃ and pH 6.5-7.5 in a dark place for 24 hours.

9. Use of a method according to any one of claims 1 to 8 for controlling the level of halogenated disinfection by-products in the field of water treatment.